/**
 *
 * Copyright (c) 2005, European Commission project OneLab under contract 034819 (http://www.one-lab.org)
 * All rights reserved.
 * Redistribution and use in source and binary forms, with or 
 * without modification, are permitted provided that the following 
 * conditions are met:
 *  - Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer.
 *  - Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in 
 *    the documentation and/or other materials provided with the distribution.
 *  - Neither the name of the University Catholique de Louvain - UCL
 *    nor the names of its contributors may be used to endorse or 
 *    promote products derived from this software without specific prior 
 *    written permission.
 *    
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 * POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.lin.benchmade.bloom;

import java.util.BitSet;

public class BloomFilter {

	private final int vectorSize;
	private final Hash hash;
	private final int numHash;
	private final BitSet bits;

	public BloomFilter(int vectorSize, int numHash, int hashType) {
		this.vectorSize = vectorSize;
		this.numHash = numHash;
		bits = new BitSet(vectorSize);
		hash = Hash.getInstance(hashType);
	}

	public void add(byte[] key) {
		if (key == null) {
			throw new NullPointerException("key cannot be null");
		}
		int[] h = hash(key);
		for (int i = 0; i < numHash; i++) {
			bits.set(h[i]);
		}
	}

	public boolean contains(byte[] key) {
		if (key == null) {
			throw new NullPointerException("key cannot be null");
		}

		int[] h = hash(key);
		for (int i = 0; i < numHash; i++) {
			if (!bits.get(h[i])) {
				return false;
			}
		}
		return true;
	}

	@Override
	public String toString() {
		return bits.toString();
	}

	private int[] hash(byte[] k) {
		if (k == null) {
			throw new NullPointerException("buffer reference is null");
		}
		if (k.length == 0) {
			throw new IllegalArgumentException("key length must be > 0");
		}
		int[] result = new int[numHash];
		for (int i = 0, initval = 0; i < numHash; i++) {
			initval = hash.hash(k, initval);
			result[i] = Math.abs(initval % vectorSize);
		}
		return result;
	}
}
